EVENING. Health.

Battling Chronic Fatigue

Six months ago a single intravenous treatment of the painkiller lidocaine rescued Carol Hale from, as she describes it, "feeling like a vegetable."

Hale, 59, of Yucaipa, Calif., had been unable to get out of bed, think or walk as a result of chronic fatigue syndrome. "I felt energy for the first time in years," she says.

Her physician, Jay Goldstein, a clinical researcher in Anaheim Hills, Calif., discovered that lidocaine and many other drugs used for other conditions bring quick relief of symptoms associated with chronic fatigue syndrome.

Gradually, chronic fatigue syndrome, one of medicine's most baffling mysteries, is yielding up its secrets. New studies have shed clearer light on who gets it. New hypotheses have emerged to explain what causes it and how it affects the body. And some promising treatments are in clinical use or being tested.

Chronic fatigue was until recent years dismissed by many doctors as "yuppie flu," because it seemed to affect mostly young, white professionals.

However, new studies by the federal Centers for Disease Control and Prevention have shown that chronic fatigue is more common among blacks and Native Americans than among whites; that it is more common among women than men, and that the average sufferer makes $15,000 a year.

Estimates on the incidence range from 76 of every 100,000 Americans to as many as 220 of 100,000.

Diagnosis is especially tricky because symptoms tend to worsen and abate in cycles, although many patients remain severely debilitated for years.

However, new diagnostic guidelines have made identifying chronic fatigue easier.

The diagnosis requires four or more symptoms at the same time. These may include overwhelming fatigue, tender lymph nodes, joint pain without swelling, muscle pain, headaches, non-restorative sleep, and impaired short-term memory or concentration.

"What knocks people out of work is a lost ability to form new memories and to concentrate," says Dr. Linda Miller Iger, a clinical and neuropsychologist at South Coast Medical Center, Laguna Beach, Calif., who has conducted research in the psychological effects of chronic fatigue.

Valerie Dufresne, 40, group leader of the Chronic Fatigue Syndrome Support Group of Riverside County, says a loss of concentration finally forced her to give up her law practice.

One theory holds that many symptoms occur when the body's defenses somehow get into an overactive state. In other patients, the immune system appears suppressed.

Dufresne, for example, was found to have too few natural killer T-cells, a vital part of the body's defenses. At the same time, tests showed that some parts of her immune system were fighting as if under constant attack.

Goldstein, director of the Chronic Fatigue Syndrome Institutes in Anaheim Hills, is among the researchers who argue that the immune system doesn't play a major role in chronic fatigue cases.

According to Goldstein, chronic fatigue and related disorders occur when the brain misinterprets the relevance of sensory information. Faulty sensory input throws body systems out of whack, creating feelings they don't work right.

"Walking up a flight of stairs feels like climbing a mountain," he says.

The problem, Goldstein suggests, is too little norepinephrine and too much substance P, two key brain chemicals having opposite effects on how the brain handles sensory input.

Another controversial hypothesis, based on studies at Johns Hopkins School of Medicine, blames some chronic fatigue cases on a low blood pressure disorder caused by faulty signals from the central nervous system.

In some patients blood pressure drops so steeply that the brain's oxygen supply is compromised. Those affected experience many classic chronic fatigue symptoms such as dizziness, light-headedness, and extreme tiredness after standing a long time.